1. Field of the Invention
The present invention relates to an image stabilizing apparatus that corrects an image blur caused by hand shake.
2. Description of the Related Art
As one method of correcting a shift of an optical axis that is generated by hand shake at the time of photography to perform an optical image stabilization in a lens barrel of an optical apparatus such as a digital camera, there is a method of performing a shift movement of an image stabilizing lens in a plane orthogonal to the optical axis.
In a shift unit that has two drivers that drive a shift member in a vertical direction (hereinafter, referred to as a “pitch direction”) and in a horizontal direction (hereinafter, referred to as a “yaw direction”) in the plane orthogonal to the optical axis respectively, a change of a position of one of the drivers causes a generation of a pullback force of the other one of the drivers. Japanese Patent Laid-Open No. 2002-196382 discloses an image stabilizing apparatus that is configured so as to reduce the pullback force in a pitch direction driver. In this image stabilizing apparatus, a yoke is provided with a protrusion shape that is protruded to an optical axis direction. A size of a magnetic force is inversely proportional to square of a distance. Accordingly, when the shift member moves on the plane orthogonal to the optical axis to change the distance between a drive magnet and a protrusion shape, the pullback force applied to the protrusion shape is applied in a direction where the movement is facilitated.
However, since the pullback force is generated in the yaw direction driver even in this case, a moment that rotates the shift member in the plane orthogonal to the optical axis is generated and the shift member freely rotates during the image stabilizing operation. If the shift member contacts a fixed member due to the rotation movement, a collision noise and an image disturbance are generated in some cases. When parts are damaged by the contact, the subsequent drive of the shift member may be affected. Accordingly, an interval between the shift member and the fixed member needs to be widened so that the shift member does not contact the peripheral fixed member even when it rotates. However, this causes an increase of the size of each part and also leads to an increase of the size of a lens barrel.
Furthermore, if the shift member significantly rotates, characteristics of an output of a position detection sensor change and accurate position detection cannot be performed, and as a result, a so-called crosstalk is generated. The change of the position detection caused by the rotation leads to an oscillation of a feedback position control in some cases, and it causes a deterioration of an optical performance at the time of the image stabilizing operation. For example, Japanese Patent No. 3229899 discloses an image stabilizing apparatus that is provided with a guide shaft for restricting the rotation of the shift member.
However, as disclosed in Japanese Patent No. 3229899, when the guide shaft is provided as a member of suppressing the rotation of the shift member in the plane orthogonal to the optical axis in order to improve a driving performance, the reduction in size of the image stabilizing apparatus is prevented. Additionally, it is difficult to reduce the cost since the number of parts is increased by complicating the configuration of the apparatus.